Doris,2016.6.11,precision and accuracy dart figure

Edit 0 6 … 
import turtle
import random
alex = turtle.Turtle()
wn=alex.screen
alex.shape('classic')
i = 110
radius = 10
alex.penup()
alex.goto(0,-1*(i-radius))
alex.pendown()
alex.speed(0)
step=0
while i > radius:
    step += 1
    i -= radius
    if step % 2 == 1:
        alex.fillcolor('red')
    else:
        alex.fillcolor('white')
    alex.begin_fill()
    alex.circle(i)
    alex.write(step)
    alex.end_fill()
    alex.penup()
    alex.left(90)
    alex.forward(radius)
    alex.pendown()
    alex.right(90)
print('center point of circle is (o,o) the radius of circle is ',step*radius)
left=int(input('left_limit:'))
right=int(input('right_limit:'))
lower=int(input('lower_limit:'))
upper=int(input('upper_limit:'))
times=int(input('times:'))
for n in range (times):
    while 1:
        a=random.uniform(left,right)
        b=random.uniform(upper,lower)
        if (a**2+b**2)**0.5<100:
            alex.penup()
            alex.goto(a,b)
            alex.pendown()
            alex.stamp()
            break
wn.mainloop()